Hiro is Makoto's best friend since -- well, forever. Hiro is quiet, yet kind. He always helps underclassmen whenever they are lost or in need of help. Hiro use to get into a lot of fights as a kid, so he is well-capable of defending himself when needed to. He is mysterious when it comes to his home life, as no one seems to mention his parents. There are rumors saying he lives by himself because his parents neglect him, but there is no confirmation this is true. 

Hiro has a low and quiet voice, and doesn't like screaming, so he only raises his voice a little when he's angry, to keep his 'chill' nature.